ahci: increase timout

[oshogbo]

Summary

For some devices, like Marvell 88SE9230, it takes more time
to connect to the device. This patch introduces a special flag
that extends the timeout from around 100ms to around 500ms.

This change is a follow-up to https://reviews.freebsd.org/D37585, in which Warner suggested changing how the timeout is implemented.
I agree that the idea given by Warner is a better approach. However, we would like to land this more straightforward patch before the new release (and more uncomplicated to test and understand) and then work on converting the whole driver to the way suggested by @imp after this landed in a release.

This change is based on the work of: Peter Eriksson <[e-mail]>
PR: 243401
Sponsored by: Klara, Inc.
Sponsored by: SkunkWerks, GmbH

[thj]

sys/dev/ahci/ahci.c

2610–2615

Is this clearer:

'Wait for "connect well", up to 100ms by default and up to 500ms for devices with the SLOWDEV quirk.'

[allanjude]

sys/dev/ahci/ahci.c

158

while the comment is updated, the code still appears to do 25ms * 80 = 2 seconds

[oshogbo]

sys/dev/ahci/ahci.c

158

This time is ok, I screw up the comment fix. Suggested in PR.

[imp]

I like this a lot more than the prior submission. This has cleaned up very nicely. Thank you so much for the time and effort to do so.
I have some qualms about the long delays, but they aren't insane and should be rare enough that the tight loop shouldn't cause operational issues.